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How to monitor tempreture in a Behmor - Probe Placement

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  • How to monitor tempreture in a Behmor - Probe Placement

    Hi Roasters

    After trawling through as many threads as I could find, I thought I would try and consolidate some of the questions relating to adding the USB Dataloggin thermocouple to a Behmor Roaster.

    What I have found is a good sticky thread on the USB Logger, Information on the CS roasting software and a good template
    for drilling the Behmor.

    Now as someone that is about to go down the same path, I have been wondering about a few aspects.

    Firstly, relating to the different kinds of temp probes.
    When you buy the USB logger from bean bay, you will receive a multi-meter which has what’s called the Thermocouple Bead and a probe called Twisty Cord Thermocouple Probe

    now, from my understanding. It seems that the Bead probe is good for measuring air temp.

    I’m not exactly sure what the twisty cord one is used for, but I can only assume you could place this in the beans if you were using a Corretto or similar.

    Available on the bean bay is also
    Thermocouple Probe Stainless Braid 25mm and a 100mm

    this seems to be the probe that is suggested in the sticky thread when you drill a Behmor

    Placement of probes.
    Now, from what I have found, you can either use the bead probe of the stainless steel probe (if you drill)
    for those that don’t want to drill (like me) it sounds like a viable alternative to use the bead.
    The problem is that is hard to find a place for the bead. I have tried the following 3 locations
    Also; the cable on the bead does not melt as it can withstand very high heat.
    1) Under the chaff tray (placed on the oven bed, and the chaff tray inserted onto)
    2) On top of the chaff tray (in-between the metal flippy things that move up and down on the chaff tray)
    3) Twisted around the left hand side bracket that hold the roasting drum.


    What I found was none of them got anywhere near 200 deg, I’m guessing that 200 deg is the ideal temp for start of FC (based on the roasting spreadsheet)

    Placement under the chaff tray only read to about 110 max...
    Roast profile after first roast (placed under chaff tray)
    Click image for larger version

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    Placement on top of the chaff tray read to around 140-150

    Placement on the bracket read to around 189 deg.
    Roast 3 -
    Click image for larger version

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    Are these temperatures normal?

    Would I get a better result on my reader if drilled the Behmor. I don’t think that it will be much better with the stainless steel probe?

    I understand this is a lot of questions but I think it would be helpful to others looking to do the same.

  • #2
    Hi Ggoosen
    While I don't have a Behmor (I use a corretto where I do measure bean mass temp) the theory for a DMM and Andy's software is pretty much the same.

    The probe (bead or probe) simply allows you to measure and record what is happening in any given roaster - while the cupping allows you to work out whether it was a success or not.
    So, no matter where you place the probe (within reason of course!) you simply record the time & temp that 1C starts, and then the time & temp when 2C starts, and you now have a 'profile' that you can compare with your next roast. If that 'profile' tastes foul - you change it. If it's great - try and replicate it!

    It just takes an adjustment in thinking, to be certain. My 1C starts at 200° on the knocker - but if yours is at 130°, that doesn't matter - as long as you know that's the temp it occurs at, and can adjust your techniques around these numbers :-)

    I'm sure lots of other Behmors owners will have their own ideas on placement - but the theory of profile is nothing magical - just a way of recording what works and doesn't ;-)

    Good luck
    Matt

    Comment


    • #3
      Thanks a lot Matt.

      The point your making is a very good one, that being the consistency is more important than the actual temperature.

      The only other benefit that placement could bring would be relating to comparing notes with other Behmor roasters

      Comment


      • #4
        Originally posted by DesigningByCoffee View Post
        Hi Ggoosen
        My 1C starts at 200° on the knocker -
        Interesting Matt, we must have our Coretto's set up in a similar way, I invariably hit FC @ 200c on the knocker.

        I'm using a single loaf Breville with one of Andy's DMM's positioned so that it just clears the paddle, my usual roast size is 725 grams of green.

        Roasts are very consistent.

        Comment


        • #5
          Originally posted by ggoosen View Post
          Thanks a lot Matt.

          The point your making is a very good one, that being the consistency is more important than the actual temperature.

          The only other benefit that placement could bring would be relating to comparing notes with other Behmor roasters
          Too true. I have corretto compadre's with slightly different temp settings - does make a little tricky! But the 1C/2C points and the time in between level out a fair few of those issues.

          Comment


          • #6
            Originally posted by Yelta View Post
            Interesting Matt, we must have our Coretto's set up in a similar way, I invariably hit FC @ 200c on the knocker.

            I'm using a single loaf Breville with one of Andy's DMM's positioned so that it just clears the paddle, my usual roast size is 725 grams of green.

            Roasts are very consistent.
            Sounds like it :-)
            BBM100 - the corretto modders champion! (move two spade terminals to a switch for constant mix!)

            Although, going from 350g batches to 700g batches required me to move the probe higher in the pan by about 25mm - so I now have two holes for different batch sizes. When I did my first 700g batch - everything (1C, 2C) read 8-10° lower, proving the point really!

            But I do prefer the consistency - especially when comparing results within my own system!

            Comment


            • #7
              Originally posted by DesigningByCoffee View Post
              Sounds like it :-)
              BBM100 - the corretto modders champion! (move two spade terminals to a switch for constant mix!)
              That's the one.

              Comment


              • #8
                Originally posted by DesigningByCoffee View Post
                Sounds like it :-)
                BBM100 - the corretto modders champion! (move two spade terminals to a switch for constant mix!)

                Although, going from 350g batches to 700g batches required me to move the probe higher in the pan by about 25mm - so I now have two holes for different batch sizes. When I did my first 700g batch - everything (1C, 2C) read 8-10° lower, proving the point really!

                But I do prefer the consistency - especially when comparing results within my own system!

                What does the probe messaure is it ambient tempreture or the bean temp?

                Im guessing your probe is in the beans slightly and slighty out right?

                Comment


                • #9
                  Originally posted by ggoosen View Post
                  What does the probe messaure is it ambient tempreture or the bean temp?

                  Im guessing your probe is in the beans slightly and slighty out right?
                  No. Basically the ss probe is a bead type jobby inside a steel tube. So it only measures right at the tip I believe. My probe goes from outside the BM, right through all the housings and right into the pan, and right into the bean mass itself near the paddle - so no air exposure at all. Plus my corretto is all sealed, so even more accurate. That's why my profiles are quite consistent with many other roasters who can measure bean mass temp - it is pretty consistent.

                  But in the behmor, there is no way to get into the bean mass (though some are pondering!) so you have to translate your findings. But I think this is even the case with commercial drums? They measure exhaust and drum air temp - not bean mass (same issue as the behmor - where do you put the probe into a turning drum!) But 1C & 2C will happen at the same bean temp in the behmor - you just won't be able to align the readings from your probe exactly :-)
                  Matt
                  Last edited by DesigningByCoffee; 5 September 2013, 04:34 PM.

                  Comment


                  • #10
                    The typical 200 degrees FC temps that the coretto and other roasters often talk about is usually measured at the beans, (the probe is amongst the beans)
                    In the behmor oven, you are only going to be able to measure air temp because it is not that easy to get a probe amongst the beans which is why your numbers are so different.
                    The temps you are seeing are correct for air temp measurements so everyone else's numbers are not so important. After finding a probe position that you are happy with, just keep it consistent and use those numbers for your baseline.
                    Another thing to be aware of is that actual bean temps are the most accurate in regards to predicting FC/SC but unfortunately for us behmor roasters, obtaining bean temps is almost out of the question with a drum roaster.
                    Using the air temp is really only useful as a guide as it is greatly effected by ambient temps and lots of other factors resulting in FC/SC times that aren't always consistent.

                    Comment


                    • #11
                      Thanks fg, the position I have it in now is pretty good. Over the holder for the basket on the lhs

                      I found that under the chaff , the temps were much slower to react, which might be a good or a bad thing. Have you drilled your Behmor

                      Comment


                      • #12
                        How to monitor tempreture in a Behmor - Probe Placement

                        I've got two probes in mine: one in the "coffeesnobs location" (top left of chamber) and one under the tray.

                        The one in the open air clearly shows fans coming on and off, and reacts quickly to any changes to elements/door/fan. The one under the tray is much slower to respond... and I feel this probably more accurately reflects how the beans themselves are going.

                        I probably need to collate some more data to say definitively (ask me in another 50 roasts or so), but I think as long as you can mark a similar temp each time for 1C/2C you'll find the probe useful.

                        Comment


                        • #13
                          Originally posted by ggoosen View Post
                          Thanks fg, the position I have it in now is pretty good. Over the holder for the basket on the lhs

                          I found that under the chaff , the temps were much slower to react, which might be a good or a bad thing. Have you drilled your Behmor
                          I have drilled mine as per the CS template but I find my other probe which is under the chaff tray more useful as it reacts slower sort of like how I'd expect the bean temp to react.
                          I've also started experimenting with placing a probe in one of the exhaust perforations. I've only done 1 roast like this and noticed the under chaff and exhaust readings weren't too far off each other.
                          Still need to do more tests to determine if this suits my requirements.

                          Comment


                          • #14
                            Hello, I have another experiment about placing the probe.
                            Today I placed the bead probe through the axis into the beans and it was quite easy.

                            I drilled through the axis 3.2mm, 4mm the inside housing, 5mm the outside housing,
                            Inserting the wire probe. A bit fumbling until it was a bit inside the beans and only slight contact to blades.

                            The graph looks much like what I saw on several places.
                            Continous increase, First cracks 195°-210°, max temp at the end 226 (begin second crack?)
                            Accuracy and long term damage risk for the probe is not clear to me.

                            Using just the wire bead probe seams to be very sloppy, but it allows flexibility and avoids damage, even if the bead stucks in a hole of a bead or the drum grid (just tested today)
                            The more beans - the easier it should be to avoid the blades. I roasted 330g - a bit tricky, a full pound should be easy and save.
                            Peter

                            Comment


                            • #15
                              That sounds pretty spot on for a bean mass profile Peter. Well done!
                              You'll have to post a pic of what it looks like inside the Behmor - I'm sure there would be many interested snobbers
                              Cheers Matt

                              Comment

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